Non-stopwords lemmas; showing up to 1000th most frequent word. The colors correspond to the rank (dark purple higher, yellow is lower), but importantly, rank of the previous year subcorpus - so effectively a smooth gradient of colors indicates little yearly changes in the ranking of words, while “random” looking messy colors indicate changes since the previous year; a bright yellow dot appearing far left indicates sudden increase in a new or low-rank word (e.g. cotton in 1870). Note log scale of frequency axis. Click “play” or manually move the slider. Hover over points to see words, drag box to zoom.

Movement of one presumably world-events driven word, war: